test doctype unregistration must not NPE if still pending

18:12:22,620 ERROR [RegistrationInfoImpl] Failed to unregister extension. Contributor: RegistrationInfo: service:org.nuxeo.ecm.platform.routing.graph.types.test to service:org.nuxeo.ecm.core.schema.TypeService; xpoint: doctype
java.lang.NullPointerException
	at org.nuxeo.ecm.core.schema.registries.DocumentTypeRegistry.getContributionId(DocumentTypeRegistry.java:45)
	at org.nuxeo.ecm.core.schema.registries.DocumentTypeRegistry.getContributionId(DocumentTypeRegistry.java:1)
	at org.nuxeo.runtime.model.ContributionFragmentRegistry.removeContribution(ContributionFragmentRegistry.java:205)
	at org.nuxeo.runtime.model.ContributionFragmentRegistry.removeContribution(ContributionFragmentRegistry.java:181)
	at org.nuxeo.ecm.core.schema.SchemaManagerImpl.unregisterDocumentType(SchemaManagerImpl.java:357)
	at org.nuxeo.ecm.core.schema.TypeService.unregisterExtension(TypeService.java:177)
	at org.nuxeo.runtime.model.impl.ComponentInstanceImpl.unregisterExtension(ComponentInstanceImpl.java:224)
	at org.nuxeo.runtime.model.impl.ComponentManagerImpl.unregisterExtension(ComponentManagerImpl.java:307)
	at org.nuxeo.runtime.model.impl.RegistrationInfoImpl.deactivate(RegistrationInfoImpl.java:417)
	at org.nuxeo.runtime.model.impl.RegistrationInfoImpl.unresolve(RegistrationInfoImpl.java:462)
	at org.nuxeo.runtime.model.impl.ComponentRegistry.unresolveComponent(ComponentRegistry.java:212)
	at org.nuxeo.runtime.model.impl.ComponentRegistry.removeComponent(ComponentRegistry.java:141)
	at org.nuxeo.runtime.model.impl.ComponentManagerImpl.unregister(ComponentManagerImpl.java:191)
	at org.nuxeo.runtime.model.impl.DefaultRuntimeContext.destroy(DefaultRuntimeContext.java:188)
	at org.nuxeo.runtime.osgi.OSGiRuntimeService.doStop(OSGiRuntimeService.java:200)
	at org.nuxeo.runtime.AbstractRuntimeService.stop(AbstractRuntimeService.java:144)
	at org.nuxeo.runtime.api.Framework.shutdown(Framework.java:176)
	at org.nuxeo.runtime.test.NXRuntimeTestCase.wipeRuntime(NXRuntimeTestCase.java:344)
	at org.nuxeo.runtime.test.NXRuntimeTestCase.tearDown(NXRuntimeTestCase.java:181)